The present invention relates to compositions which can notably be utilized as multifunction additives for engine fuels and which are obtained by the reaction of at least one succinic acid or anhydride with successively at least one hydroxyimidazoline and at least one polyamine.
The use of conventional fuels very often leads to the fouling of the various engine parts. Due to the incomplete vaporization and combustion of the fuel in the inlet system and/or in the combustion chamber and to the presence of lubricant traces.
In the inlet system, the accumulation of these deposits can thus occur at the level of the injectors, the carburetor and the inlet valves.
Such an accumulation has harmful consequences on the level of driving pleasure, with the appearance of an unsteady idling and misfires in spark ignition engines, as well as on the level of optimum running of the engine through the modification of the fuel-air ratio owing to the adsorption-desorption phenomena of the fuel on the formed deposits.
In order to remedy this fouling, it is possible to carry out a periodic cleaning of the affected parts, especially the valves, which is particularly costly.
The accumulation of deposits in engines and particularly on inlet valves can also be reduced by using fuels which contain certain additives, for example, detergent-type additives that are possibly combined with, for example, anticorrosive or antideposition additives for combustion chambers.
Additives, which are well-known in trade, for example, those of the polyisobutene-amine type, are usually associated with a mineral or a synthetic oil and may lead to an increasing fouling of the combustion chambers and thus to an increase in the octane requirement of the engine, with a higher sensitivity to knock phenomenon.
Among the numerous additives described in prior art, one can cite the products of the condensation of polyalkenylsuccinic anhydrides and polyamines, such as, for example, tetraethylenepentamine, which are particularly described in U.S. Pat. No. 3,172,892. These additives show good results as far as anticorrosive properties are concerned, but they are not efficient as valve detergents.
One can also cite the products of the condensation of polyalkenylsuccinic anhydrides and hydroxyimidazolines, and particularly 1-(2-hydroxyethyl) imidazolines substituted in position 2 by an alkyl or an alkenyl group, such as those which are described in EP-A-74,724. The products described in this application are good additives for engine fuels and their anticorrosive action is considerable, but they are not very efficient at the level of the carburetor detergency.